Truss testing method and apparatus



May 19, 1970 J. c. JUREIT TRUSS TESTING METHOD AND APPARATUS 2Sheets-Sheet 1 Filed Aug. 8, 1968 cc D com INVENTOR- JOHN CALVIN mm BY$311M M TE 1: a a 3 3 A: m w. h 5 3 E m a a 25 2 k: A. Ti 7/ ii 3 E n 5y 8 0: m2 vm vm S 5 NO 2% ATTORNEYS May 19, 1970 J. c. JUREIT 3,512,404

TRUSS TESTING METHOD AND APPARATUS Filed Aug. 8. 1968 2 Sheet-Sheet 2United States Patent 3 512,404 TRUSS TESTING MllTl-IOD AND APPARATUSJohn Calvin Jureit, Coral Gables, Fla., assignor to Automated BuildingComponents, Inc., Miami, Fla., a corporation of Florida Filed Aug. 8,1968, Ser. No. 751,244 Int. Cl. G01n 3/08 U.S. C]. 73-88 13 ClaimsABSTRACT OF THE DISCLOSURE The present invention includes a jig carryingwooden structural elements clamped in position to form a truss.Connector plates are applied at the joints thereof as by a press. Afterunclamping the compl ted truss and While retaining it on the jig, afluid operated piston and cylinder applies a force at the peak of thetruss as well as at the panel points (except at heels) toward the lowerchord members. Reaction plates butt the heel portions of the lower chordto prevent lateral movement of the truss. Gauges proportional to thestrain are located at opposite ends of the truss and gauges measuringtruss deflection are located below the truss peak, the central portionof the lower chord and the panel joints along the lower chord. Strainand deflection can be measured and correlated with the applied load todetermine if the structural elements are capable of withstanding theirdesigned loads. Indicia are provided on the jig to measure the recoveryof the truss to its original configuration after the test load isremoved to provide a measure of overall truss integrity and elasticity.

The present invention relates to an apparatus and method for pretestingload bearing structural members and particularly to an apparatus andmethod for loading wooden trusses before use and determining thecapability of the trusses and their structural elements to withstandtheir designed loading.

In recent years, the building trades have shown a marked trend towardprefabrication, particularly in the construction of relatively low costhousing. Various frame portions of such houses have been preassem'bled,the most common prefabricated element probably being the roof truss.This prefabrication itself has undergone an evolution from hand nailingand bolting of structural elements forming the roof truss to the vastlyimproved method of construction made possible by the advent ofstructural butt joints formed with unitary connector plates of the typedescribed in U.S. Pat. No. 2,877,520 issued Mar. 17, 1959.

In a large proportion of all presently constructed roof trusses, thelumber or structural elements forming the parts of the truss are precutand assembled on a jig or frame which clamps the lumber or el ments inposition for the application of connector plates at the butt joints. Theconnector plates, preferably of the foregoing type, are usually appliedon opposite sides of the butt joints and embedded into such elements bya pressing operation. In one method, the jig comprises a jig table whichcarries the truss along a conveyor below a press, the press beingactuated as each joint passes thereunder to embed the associated plates.This method is illustrat d in U.S. Pat. No. 3,238,867 of common assigneeherewith. Other types of truss fabricating systems employ a portablepress which is movable about the jig assembly and applied at each jointof the pre-assembled truss to embed the connector plates. Still othersprovide a plurality of movable presses disposed at locations generallycorresponding to the joint locations and, when located, stamp theconnector plates into the joints.

3,512,404 Patented May 19, 1970 ICC With the formation of prefabricatedtrusses being automated to this extent, there has arisen the need totest the trusses before installation and use to determine whether or notthe prefabricated truss as a whole and the lumber elements forming thetruss in particular can withstand the designed loading. It sometimesoccurs that the truss joints are improperly formed and/or thatirregularities in the particular truss elements, such as knots, improperseasoning and the like, are present, all of which would affect thestrength, elasticity, and integrity of the truss and the defective trusselements to the extent that the truss or one or more of its elementscannot carry the designed loading. Pretesting or preloading the trussbefore installation and the use to insure the integrity, effectiveness,and capability of the truss as a whole and the truss membersindividually, i.e., to insure that the joints are properly formed andthat the working stresses in the truss elements are well below thefracture stresses, is not generally practical in the building industry,sometimes resulting in defective trusses. Where trusses are pretested,it has proved time consuming and expensive, and, in general, there is noreally effective and eificient mechanism available prior to the presentinvention for preloading and testing the truss before use. In the singleknown previous method of pretesting the truss, selected trusses areusually positioned upright and supported at their heel portions as inuse and loaded, for example, with heavy cinder block, to a predeterminedload in the range of their working stresses or designed loads todetermine if fracture occurs. This has proven generally unsatisfactoryas each truss cannot be economically tested in this manner or all thepieces generally cannot be recovered if fracture of one or more of thepieces occurs, whereby a considerable quantity of lumber would bewasted.

In accordance with the present invention, each truss can be convenientlytested to determine overall truss integrity and to determine theexistence of and locate defects in the various structural elementsforming the truss. This can be accomplished without loading the truss toits designed load and without removing the truss from the.

jig. To this end, the present invention provides a jig assembly on whichthe lumber pieces forming the truss are assembled in the truss patternwith the connector plates disposed on opposite sides of the joints. Theplates are embedded into the truss by any one of the methods describedpreviously. Transverse reaction pads are provided on the jig assemblyagainst which heel portions of the base chord butt. Fluid actuatedcylinders are carried by the jig assembly and apply a predeterminedloading to the panel joints along the top chords of the truss (heeljoints excepted) in the direction of the lower truss chord therebyproviding loadings equivalent to the loadings encountered under actualloading conditions.

By locating an extensometer at both ends of the truss, the axialelongation or total strain on the lower chord member can be measured. Bycalculating the strain from theoretical and/or empirical considerationson a lower chord member of known length and type of wood for apredetermined applied loading on a specified truss, it can be seen thatthe measured total strain on the lower chord member for lumbersubstantially free of defects should lie close to the calculated strainor at least within a predetermined range of acceptable strain values forthe applied loading. Thus, a measured strain value above both thetheoretical or empirically calculated strain value and beyond theacceptable range of strain values for the given loading, type of lumberand truss, and length of chord, indicates an unacceptable elongation ofthe lower chord member. The area of the lower chord in which theexcessive elongation occurs, such as, for example, at a knot, can mostoften be located visually. The lower chord can then be reinforced 'byapplying one or more reinforcing plates of the type employed in formingthe truss joints in the area of the defect in a manner as set forth inmy copending application Ser. No. 282,300, filed May 22, 1963. In thismanner, the otherwise defective truss can be saved and reinforced tocarry its designed loading without tearing the truss down or wastinglumber by rejecting the defective piece.

A measured strain value less than the calculated strain value or belowthe acceptable range of strain values may indicate that the lower chordmember is not being subjected to the designed tensile loading. This maybe caused by an unacceptable compression of one or both of the upperchord members or unusual compression strength exhibited by one or moreof the truss web members. Here again, the defect can most often belocated visually and, when located, can be corrected by applying one ormore connector plates in the area of the defect. Again, the trusselements are not fractured and, instead of rejecting the entire truss,the truss can be reinforced at its defective areas and utilizedsimilarly as other non-defective trusses.

Further to the present invention, displacement measuring devices aredisposed to measure the deflections of the panel joints at the apex ofthe truss and along the upper truss chords (heel joints excepted) whenthe truss is subjected to the applied loading as before. The deflectionof these upper panel joints is proportional to the strain in both upperchord members and the magnitude of such deflection for a given truss canbe calculated from theoretical and/or empirical considerations.Accordingly, for a given truss subjected to a predetermined appliedloading in the manner as set forth previously, measured deflections ofthese upper panel joints above the calculated deflections or beyond anacceptable range of deflections for each such joint indicatesunacceptable compression of the upper chords or the intermediate webmembers. Again, the defective area can usually be visually located andreinforced as before.

Other deflection measuring gauges are disposed medially between the endsof the bottom chord member and at the lower panel joints (heel jointsexcepted) to measure the bow or deflection of the truss under theapplied loading. Again, theoretical and/or empirical considerations canprovide calculated or expected deflections for a given truss subjectedto a predetermined loading. By a correlation of the readings on thestrain and deflection gauges, the defective member can be readilylocated, i.e., it can be determined that either the bottom chord member,the upper chord members,-or the intermediate web members are defective.For example, if one of the upper chord members is defective, andcompresses to a larger extent than expected or calculated under theapplied load ing, the measured strain at the ends of the lower chordmembers will be less than the calculated strain or below the acceptablerange of strain values for such loading, and the measured deflection atthe panel joints along the upper chords and along the lower chord memberwill be greater than their calculated deflection or the correspondingacceptable range of deflections. Conversely, if one or more of the webmembers are defective in compression, the measured strain at the ends ofthe truss will be higher than the calculated strain or above theacceptable range of strain values and the measured deflection of thelower chord member will be less than its calculated deflection or belowthe acceptable range of strain values for such applied loading. Once thedefective member is located, it can either be replacedor readilyreinforced as by the application of additional plates of the foregoingdiscussed type.

Further to the invention, the amount of recovery of the truss to itsoriginal configuration after the test load is removed provides anexcellent measure of the overall integrity and elasticity of the truss.This can be readily determined by recording and comparing the deflectionreadings on the gauges before the test load is applied and after it isremoved.

Accordingly, it is a primary object of the present invention to providea method and apparatus for preloading prefabricated trusses and the likebefore installation and use.

It is another object of the present invention to provide an apparatusand method for testing prefabricated trusses and the like which isreadily and conveniently accomplished while the trusses are assembled ontheir jig tables.

It is still another object of the present invention to provide anapparatus and method for testing prefabricated trusses wherein adefective truss member can be readily identified.

It is a further object of the present invention to provide an apparatusand method for testing prefabricated trusses wherein the trusses neednot be loaded to their designed load in order to determine theeffectiveness of the truss and the truss members.

It is a related object of the present invention to provide an apparatusfor testing prefabricated trusses, including a fluid actuated cylindercarried by the jig assembly for applying a predetermined load to thetruss while the truss is on the jig assembly in a manner similar toactual loading conditions, together with strain and deflection measuringgauges carried by the jig assembly for measuring the lateral strain onand load induced deflections of the truss.

It is still a further object of the present invention to provide anapparatus and method for testing prefabricated trusses whereby a measureof the overall elasticity and integrity of the truss can be obtained.

It is still a further object of the present invention to provide anapparatus and method for testing prefabricated trusses having theforegoing characteristics wherein the load applying mechanism and thestrain and deflection measuring gauges are movably carried by the jigassembly whereby the manufacture and testing of a large variety ofdifferent sizes and shapes of wooden structures on the same jig withoutmajor modifications of the jig itself can be accomplished.

These and further objects and advantages of the present invention willbecome more apparent upon reference to the following specification andclaims and the appended drawings wherein:

FIG. 1 is a fragmentary plan view of a combination jig and prestresstesting assembly constructed in accordance with the present inventionand showing a portion of a completed truss subjected to an appliedloading;

FIG. 2 is a fragmentary sectional view taken about on line 22 of FIG. 1showing a truss clamping device and deflection measuring gauge;

FIG. 3 is a cross sectional view taken about on line 33 of FIG. 1;

FIG. 4 is an enlarged fragmentary plan view of the base reaction pad;and

FIG. 5 is a fragmentary vertical cross sectional view taken about online 5--5 of FIG. 1.

.DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1 of thedrawings, there is shown a jig assembly, generally indicated at 10,comprising a jig pad or pallet 12 formed of a large heavy sheet of metalor of a thin sheet of metal suitably reinforced or of any other suitablestructural material upon which the elements of the jig may be mounted.For purposes of clarity, only the center and lefthand portions of thecomplete jig assembly are shown. It will be understood, however, thatthe complete assembly consists of a righthand portion which isconstructed substantially as a mirror image of the lefthand portion.

Mounted at the center of jig pad 12 and extending transversely andvertically thereacross is a stationary vertical peak guide bar 14 whichcarries a combination peak reaction and load applying pad 16 slidablymounted for movement thereon. Extending perpendicular to the peak guide14 along the entire length of the jig pad 12 is a guide bar 18 whichslidably mounts a heel reaction pad 20, a one-third point reaction pad22, and a splice reaction pad 24. Guide bars 14 and 18 are identical inconstruction, stationary, and are illustrated in FIG. 2, whichrepresents a cross section through the lower guide bar 18.'It will beseen that guide bar 18 consists of an elongated metal strip havingflanges 26 which give the strip a generally T-shaped cross section.Guide bar 18 is secured to the jig pad 12 in any suitable manner, suchas by bolting, welding, or riveting.

The splice reaction pad 24 consists of a metal plate 28 suitably securedon top of the backing plate 30. Splice reaction pad 24 is slidablysecured to guide bar 18- by a pair of metal strips 32 having flanges 34which matingly engage the flanges 26 on guide bar 18. Strips 32 aresecured to pad 24 in any suitable manner, preferably by screws passingfrom the upper surface of plate 28 into strips 32 so that the screwheads are readily accessible and the screws may be tightened or loosenedto respectively lock or permit sliding motion of the reaction padrelative to guide bar 18. A tape 36 runs along the centerline of guidebar 18 bearing suitable indicia and a slot, not shown, is formed throughreaction pad 24 directly above tape 36 such that pad 24 may beaccurately located at any predetermined position along bar 18. The heeland one third point reaction pads 20 and 22, respectively, are similarlyconstructed with respect to their mounting on jig table 12.

Referring to FIGS. 2 and 4, an angle member 40 having a base 42 and apair of upstanding flanges 44 is slidably mounted on splice reaction padplate 28 by means of a pair of upstanding bolts 46 which project throughL- shaped slots 48 formed in the base 42 of angle member 40 and threadedinto tapped openings formed in plate 28. In this manner, member 40 canbe moved by longitudinal and transverse movement thereof between twopositions, a first position wherein flanges 44 butt the outer edge ofthe lower chord member LC. of a truss and a second position whereinflanges 44 are spaced from the lower chord for reasons as will becomeapparent. The onethird reaction pad 22 is similarly constructed as thesplice reaction pad and its angle member 49 also has a pair of spacedupstanding flanges 50. Heel reaction pad 20 mounts an angled bracket 52by means of screws, not shown, whereby bracket 52 is stationary relativeto pad 20.

Referring to FIG. 1, 2, and 4, the locking devices 54 each comprises acylindrical barrel 56 having base plates 58 suitably secured to theplates 28 of the associated pads. Slidably mounted in barrel '56 is aplunger consisting of a tube 60 having an arcuate plate 62 secured onits end. A plunger block 64 is slidably mounted in the other end ofbarrel 56 and receives a locking plunger 66 within a bore 68, theplunger 66 being biased upwardly against barrel 56 by a spring 70. Anaperture 72 is formed in the upper surface of barrel 56 to the right ofthe plunger position in FIG. 2. A leaf spring 74 is secured to the upperside of barrel 56 at 76 and has a dimple 78 at one end overlyingaperture 72.

A pair of arms 80 project from the left end of barrel 56 in FIG. 2 andmount a pivot pin 82. Pin 82 rotatably supports an eccentrically mountedcircular cam 84 having an actuating handle 86 projecting from itsperiphery. A spring 88 is mounted within tube 60 and simultaneouslyurges tube 60 to the right in FIG. 2 and block 64 to the left intoengagement against cam 84.

It will be seen that with cam 84 in the position shown in FIGS. 2 and 4,block 64 butts cam 84. If cam 84 is rotated, block 64 moves to the rightapplying pressure to tube 60 by spring 88. When plunger 66 is alignedwith aperture 72, the plunger is biased into aperture 72 thereby lockingthe block 64 in an advanced position. Cam 84 may then be returned to anunlocked position with plunger 66 retaining block 64 in the advancedposition. With block 64 in the advanced position, it will be noted thatdepression of leaf spring 74 causes dimple 78 to depress locking 6plunger 66 from without aperture 72 whereby block 64 is retracted underthe bias of spring 88 to the position illustrated in FIG. 2

Referring to FIG. 1, a pair of parallel stationary guide bars 90 aredisposed near the center and left end of jig pad 12 respectively andprovide an adjustable mounting for a horizontal one-fourth point movableguide bar 92. The left end of guide bar 92 is attached to a connectorplate 94 by a pin 96 received in a slot 98 in the connector plate. Theconnector plate per se is slidably secured to the left guide bar 90 byflanged strips of the same type illustrated in connection with splicereaction paid 24. A slot 100 is provided in connector plate 94 to view atape 102 carried by guide bar 90. The right end of guide bar 92 ispivotally secured to a second connector plate 104 by a pin 106.Connector plate 104 is slidably mounted on the central guide bar 90 inthe same manner as plate 94 and is also provided with a slot, not shown,for positioning plate 104 along bar 90.

A one-fourth point reaction pad 108 is slidably mounted on movable bar92 in a like manner as the spice reaction pad is mounted to the guidebar 18. The one-fourth point reaction pad 108 carries a lumberpositioning pin 110 and a locking device 54 similar to the lockingdevice on the spice reaction pad. The one-third point reaction pad 22carries no cam but has a lumber positioning pin 112 removably mountedthereon.

The heel reaction pad 20 is also provided with a locking device 54 whilethe peak reaction pad 16 is provided with a pair of locking devices 54on opposite sides of the peak splice. Lumber positioning pins 114 arealso removably mounted on pad 16.

A centrally located support bracket is slidably mounted adjacent theupper edge of pad 12 along peak guide bar 14 and carries a fluidoperated piston and cylinder 122, the bracket being secured to bar 14 inselected adjusted position therealong by screws, not shown. The pistonrod 123 thereof carries a V-shaped head 124 engageable against the apexof the truss formed by the butting upper chord members U.C. The reactionpad 108 also carries a fluid actuated piston and cylinder 122a and thepiston rod 123a thereof pivotally carries a head 124a engageable againstthe upper chord U.C. at the quarter panel joint. Piston heads, 124, 124aare thus extendable to apply loads to the truss in a manner equivalentto actual loading conditions. A suitable fluid pressure source, notshown, is provided piston and cylinders 122, 122a via conduits 125,125a.

In order to measure the longitudinal displacement of the ends of thetruss under the applied loading provided by cylinders 122, 122a and thedeflection of the truss at its panel joints (heel joints excepted),extensometers or displacement measuring gauges are disposed on the heel,one quarter point, one third point, and splice reaction pads 20, 108,22, and 24, respectively, and on pallet 12, the latter being in positionto measure the displacement of the truss peak. Referring now to FIGS. 1and 3, a displacement measuring gauge 126 is slidably mounted on eachheel reaction pad 20 in a key slot 128 extending parallel to guide bar18. Gauge 126 is carried by a bolt 130 having an enlarged head 131 whichis received in key slot 128. A nut 132 having a handle 133 securedthereto is threaded on bolt 130 and clamps gauge 126 in selectedadjusted position along slot 128. Gauge 126 may be of any type ofsuitable displacement measuring device, such as, for example, a dialgauge operable in response to the displacement of a plunger 134. Othertypes of mechanical micrometer type gauges or electrically responsivegauges, such as potentimeters, strain gauges, and the like could beemployed.

Similar type gauges 135 for measuring the deflection of lower chordmember LC. medially of the length of the truss and at the one thirdpanel joint, are fixed to splice reaction pad 24 and one third reactionpad 22, respectively, by screws, not shown. Gauges 135 have extendedplunger arms 137 which overlie the bases of the associated angle members40 with the heads 139 of the arms extending between the spaced uprightflanges for abutment against lower chord member L.C. A like gauge 135afor measuring the deflection at the one quarter joint panel is fixed toreaction pad 108 and its plunger arm 137a extends such that head 139abears against the joint members. A similar type gauge 140 for measuringthe deflection of the truss peak is slidably mounted along peak guidebar 14 between peak and heel reaction pads 16 and 24, respectively, by abracket 142. Gauge 140 is secured in selected adjusted position alongbar 14 by screws 143 which thread through bracket 142 to clamp theflanges 26 on bar 14 between screws 143 and inwardly directed flanges,not shown, carried on the underside of bracket 142. In this manner, whenpeak reaction pad 16 is located in a predetermined position along guidebar 14 in accordance with the size of the truss being fabricated, gauge140 can likewise be adjustably positioned along bar 14 such that thehead 1 44 on its plunger member 145 can engage the peak ends of theupper chord members of the truss, or, in this instance, the butted endsof web members W.

To employ the jig and prestress testing assembly, a series of connectorplates P of the foregoing type disclosed in US. Pat. No. 2,877,520 arespotted on the reaction pads with the teeth thereof extending upwardlyprior to setting the wooden members on the reaction pads. The woodenmembers are then disposed on top of the teeth of the plates and a secondset of connector plates is then laid on top of the wooden members withthe teeth directed downwardly so that a single pressing operation iseffective to completely form each joint of the roof truss.

With the desired dimensions of the truss known, the various reactionpads are properly positioned along their associated guide bars accordingto previous data by aligning the respective reaction pads with theappropriate indicia along their underlying tapes. The reaction pads aresecured in place on their respective guide bars by tightening theirvarious locking screws and the various chord and web members forming thetruss are then placed on the jig over the plates and secured in positionby locking the various locking devices as by moving the handles thereofto advance arcuate plates 62 to bear against the appropriate members ofthe truss. The locking devices clamp the members of the truss in placeand the handles may be returned to their previous position as lockingplunger 66 precludes retraction of plunger block 64. It will be notedthat the angle members 40 and 49 are moved toward and to a positionbutting the outer edge of lower chord member LC. The truss is now jiggedand ready for pressing and may be placed between the platens 148 of anysuitable press which, when actuated, descends to press the teeth of theplates into the wooden members to form the desired butt joints. At theend of the press stroke, the upper platen flexes leaf spring 74depressing dimple 78 to move locking plunger 66 out of aperture 72,thereby releasing plunger block 64. It will be noted that at this pointin the fabrication operation, the truss is completely assembled andcould be removed without testing.

To preload and test the truss while lying on the jig assembly, theluumber positioning pins 110 and 114 are removed and the angle members40 and 49 are moved longitudinally and then transversely to space therespective flanges thereof from the outer edge of the lower chord memberL.C. Note that the heel angle brackets 52 remain fixed to the heelreaction pads and provide end supports for the truss when test loaded inthe following manner similarly as the truss would be subjected toloading in use. The gauge readings are then recorded.

To prestress the truss, a predetermined loading, for which predetermineddata providing the strains and deflections at the various measuringpoints for such loading has been calculated and which lies well belowthe design loading, is applied by actuating the piston and cylinderarrangements 122, 122a. Piston heads 124, 124a, respectively, engage thepeak joint and the one third joint of the truss, thereby loading thetruss against the heel reaction bracket 52 with a loading equivalent tothe actual loading in use. If the truss and its structural members areeffective to carry their design loadings, the measured values asdisplayed on gauges 126, 135, a and will approximate the calculatedstrain or deflection or at least lie within acceptable predeterminedstrain or deflection limits. However, if there is a defective trussjoint or a defect in one or more of the structural members forming thetruss, the measured strain or deflections will vary significantly fromthe calculated range of strains or deflections. By correlation of themeasured strains and deflections of the various gauges and noting thevariations thereof from the calculated strains or deflections, it ispossible to determine the location of the defect.

For example, a strain reading on the heel gauge 126 greater than thecalculated or acceptable range of strains indicates an elongation of thelower chord member to larger extent than would be anticipated.Accordingly, a workman may locate the defect and apply a connector lateto reinforce the defective portion of the lower chord member in a manneras disclosed in copending application Ser. No. 282,300, filed May 22,1963. A larger deflection measurement than calculated on either thesplice or peak gauges would indicate that either the upper chord memberor web member is weak in compression and a workman may likewise locatethe defective portion of such members and similarly apply a reinforcingplate. A deflection measurement at the truss peak higher than thecalculated or accepted range of deflections coupled with a deflectionmeasurement at the splice pad lower than the calculated or acceptedrange of deflections would indicate that the web member is defective incompression and this too would be remedied in identical fashion.

A large deflection measurement than calculated at the one third or onequarter joints would indicate that a web member is weak in compressionand this may be remedied in similar fashion.

The piston heads 124, 124a are then retracted permitting the truss toreturn to its original configuration. The finished truss may then belifted from the jig, The gauge readings are again recorded and thedifference in these jreadings and the original gauge readings prior tothe test provide a measure of the overall integrity and elasticity ofthe truss.

It will be noted that only a few further steps are required to preloadand test the truss while the same lies on the jig and these steps can beaccomplished in a .minimum amount of time. Note also the locationadjustability of the piston and cylinder arrangements 122, 122a, theheel splice, peak and intermediate reaction pads, the gauge 140 alongbar 14 and gauges 126 along the heel reaction pads. In this manner,various sizes and shapes of trusses can be assembled, prestressed andtested.

What is claimed and desired to be secured by US. Letters Patent is:

1. An assembling and testing apparatus for structural wooden trusses andthe like having their members jointed together by connector plates ofthe type having teeth struck therefrom for embedment into the members,said apparatus comprising support means for the structural truss, meanscarried by said support means for holding the wooden members inpredetermined positions to form the truss, press means adjacent saidsupport means for embedding the teeth of the connector plates into thejoints formed by the prepositioned members, means for applying it loadto the completed truss, abutment means carried by said truss supportmeans and providing a reaction fon :e for preventing the truss frombeing displaced from the support means under the applied loading, and atleast one measuring gauge disposed in measuring position relative to thecompleted truss for determining a load bearing characteristic of thecompleted truss under the applied loading, said measuring gauge beingcarried by said support means adjacent the heel portion of the truss inposition to measure the elongation of the lower chord member of thetruss under the applied loading.

2. An assembling and testing apparatus for structural wooden trusses andthe like having their members jointed together by connector plates ofthe type having teeth struck therefrom for embedment into the members,said apparatus comprising support means for the structural truss, meanscarried by said support means for holding the wooden members inpredetermined positions to form the truss, press means adjacent saidsupport means for embedding the teeth of the connector plates into thejoints formed by the prepositioned members, means for applying a load tothe completed truss, abutment means carried by said truss support meansand providing a reaction force for preventing the truss from beingdisplaced from the support means under the applied loading, and at leastone measuring gauge disposed in measuring position relative to thecompleted truss under the applied loading, said measuring gauge beingcarried by said support means adjacent the lower chord member of thetruss in position to measure the deflection of the truss under theapplied loading.

3. An assembling and testing apparatus for structural Wooden trusses andthe like having their members jointed together by connector plates ofthe type having teeth struck therefrom for embodiment into the members,said apparatus comprising support means for the structural truss, meanscarried by said support means for holding the wooden members inpredeetermined positions to form the truss, press means adjacent saidsupport means for embedding the teeth of the connector places into thejoints formed by the prepositioned members, means for applying a load tothe completed truss, abutment means carried by said truss support meansand providing a reaction force for preventing the truss from beingdisplaced from the support means under the applied loading, and at leastone measuring gauge disposed in measuring position relative to thecompleted truss for determining a load bearing characteristic of thecompleted truss under the applied loading, said measuring gauge beingcarried by said support means adjacent the upper chord members of thetruss in position to measure the deflection of the upper chord memberunder the applied loading.

4. An assembling and testing apparatus for wooden trusses and the likehaving their members joined together by connector plates of the typehaving teeth struck therefrom for embedment into the members, saidapparatus comprising support means for the truss, means carried by saidsupport means for holding the wooden members in predetermined positionsto form the truss, press means adjacent said support means for embeddingthe teeth of the connector plates into the joints formed by the prepositioned members, means for applying a load to the completed truss,abutment means carried by said truss support means and providing areaction force for preventing the truss from being displaced from thesupport means under the applied loading, and at least one measuringgauge disposed in measuring position relative to the completed truss fordetermining a load bearing characteristic of the completed truss underthe applied loading, said support means including a plurality of padsfor supporting the truss at the joints thereof, said pads being mountedfor movement along predetermined paths between a plurality of trusssupporting positions to accommodate trusses of various sizes, said gaugebeing carried by one of said pads whereby the gauge is located inmeasuring position relative to a completed truss of any one of thevarious sizes thereof.

5. Apparatus according to claim 4 wherein said load applying meansincludes a fluid operated piston and cylinder carried by said supportmeans.

6. Apparatus according to claim 4 including at least two measuringgauges, one of said gauges being carried by said support means inposition to measure the strain on the lower chord member of the trussunder the applied loading and the other of said gauges being carried bysaid support means in position to measure the deflection of the trussunder the applied loading.

7. An assembling and testing apparatus for wooden trusses and the likehaving their members joined together by connector plates of the typehaving teeth struck therefrom for embedment into the members, saidapparatus comprising support means for the truss, means carried by saidsupport means for holding the wooden members in predetermined positionsto form the truss, press means adjacent said support means for embeddingthe teeth of the connector plate into the joints formed by theprepositioned member's, means for applying a load to the completedtruss, abutment means carried by said truss support means and providinga reaction force for preventing the truss from being displaced from thesupport means under the applied loading, and at least one measuringgauge disposed in measuring position relative to the completed truss fordetermining a load bearing characteristic of the completed truss underthe applied loading, said support means including an elongated jigtable, a plurality of pads for supporting the truss at the jointsthereof, said pads being mounted on said jig table for movement alongpredetermined paths between a plurality of truss supporting positionsfor accommodating trusses of various sizes, one of said paths beingmounted for substantially transverse movement across said jig table forsupporting an upper joint member of the truss, two of said pads beingmounted for substantially longitudinal movement along said jig table forsupporting heel jointed members of the truss, said load applying meansincluding a piston and cylinder carried by said jig table and operableto load the truss in a direction substantially parallel to the directionof movement of said one pad.

8. Apparatus according to claim 7 wherein said abutment means includesan abutment member carried by each of said heel reaction pads.

9. A method of assembling Wooden members to form a truss and testing thecompleted truss before use, comprising the steps of: locating thestructural members in predetermined positions on a jig assembly to forma truss pattern and thereby forming a plurality of joints between saidmembers, disposing connector plates of the type having teeth strucktherefrom adjacent at least one side of the joints of the members,embedding the teeth of the connector plates into the joints to form arigidized truss, applying a load to the rigid truss While the assembledtruss is located on the jig assembly and measuring a load bearingcharacteristic of the completed truss while the truss is subjected tothe applied loading.

10. A method according to claim 9 wherein the step of measuring includesmeasuring the endwise elongation of the lower chord member of thecompleted truss under the applied loading.

:11. A method according to claim '9 wherein the step of measuringincludes measuring the deflection of the completed truss under theapplied loading.

12. A method according to claim 9 wherein the jig assembly includes padsmovably carried thereby for supporting the truss at the joints thereofand including the steps of moving the pads relative to the table to apredetermined position for supporting the structural members of a trussof given size at the joints thereof, and moving a measuring gaugerelative to the jig assembly to a measuring position relative to thegiven truss.

13. A method of assembling Wooden members to form a truss and testingthe completed truss before use, comprising the steps of: locating thestructural members in predetermined positions on a jig assembly to forma truss 1 1 pattern and thereby forming a plurality of joints betweensaid members, disposing connector plates of the types having teethstruck therefrom adjacent at least one side of the joints of themembers, embedding the teeth of the connector plates into the joints toform a rigidized truss, applying a load to the rigid truss while theassembled truss is located on the jig assembly, measuring a load bearingcharacteristic of the completed tluss While the truss is subjected tothe applied loading, including measuring the deflection of the completedtruss under the applied loading, removing the load from the truss, andmeasuring the displacement of the truss from its original configurationafter the load has been removed.

References Cited UNITED STATES PATENTS 8/1925 Beggs 7388 5/1928 Reed7388 10/1936 Harrison 7388 2/1954 Berman 7388 US. Cl. X.R.

331 33 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,512 ,40 Dated Mav 19. 1970 JOHN CALVIN JUREIT Invcnt0r(s) It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

I Column 6, line 21, "spice" should read spl ice line 25, "spice" 1should read splice Column 7, line 64, "luumber" should read lumberColumn 9, line 32, "embodiment" should read embedment --l; line 35,

"predeetermined" should read predetermined DEL 7 i am Meat:

Edward M. Fletcher, 1'1.

Attesting Officer

